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I'm unclear on why supercritical steam is important for electrical generation. Anybody happen to know? Reading through http://en.wikipedia.org/wiki/Supercriti

I'm unclear on why supercritical steam is important for electrical generation. Anybody happen to know? Reading through http://en.wikipedia.org/wiki/Supercritical_steam_generator http://en.wikipedia.org/wiki/Supercritical_steam_generator indicates that Benson boilers are more fuel efficient (and perhaps less prone to explosion), but reduction in amount of fossil fuels used to turn a turbine seems to be sort of a moot point here. Would super critical steam generation mean a solar plant can produce more electricity? Or that a supercritical steam generating solar plant is cheaper to operate?

cossatot 12y ago
I'm not an expert here, but I believe that the maximum possible efficiency of all heat engines is governed by the temperature difference between the heat source and the heat sink [1,2]. Increasing the water T/P to supercritical both increases the T at which it can enter the system and, from what I gather by the link you posted and from [3], also results in some simplification of the plant mechanics, which likely increases efficiency as well. This should indicate that for a given amount of sunlight (or fossil fuels in a conventional power plant), a greater amount of electricity can be created. [1]: http://en.wikipedia.org/wiki/Carnot_cycle http://en.wikipedia.org/wiki/Carnot_cycle [2]: http://en.wikipedia.org/wiki/Rankine_cycle http://en.wikipedia.org/wiki/Rankine_cycle [3]: http://www.brighthubengineering.com/power-plants/32896-how-are-supercritical-boilers-different-from-subcritical-boilers/ http://www.brighthubengineering.com/power-plants/32896-how-a...
- neltnerb 12y ago
  This is the correct answer. Higher temperature steam allows a higher maximum power extraction potential.
jaggederest 12y ago
For a given megawatt of thermal energy input, you get more electrical output by working in the supercritical steam domain than you do in subcritical systems. So not 'more electricity' since the sun is functionally unlimited, but 'more electricity per square foot' or 'more electricity per heliostat' or what have you.
anthonyb 12y ago
Existing fossil fuel plants (ie. Coal) are designed for supercritical steam. If you can make that with solar, it should make retrofitting much easier.

cossatot 12y ago

I'm not an expert here, but I believe that the maximum possible efficiency of all heat engines is governed by the temperature difference between the heat source and the heat sink [1,2]. Increasing the water T/P to supercritical both increases the T at which it can enter the system and, from what I gather by the link you posted and from [3], also results in some simplification of the plant mechanics, which likely increases efficiency as well. This should indicate that for a given amount of sunlight (or fossil fuels in a conventional power plant), a greater amount of electricity can be created. [1]: http://en.wikipedia.org/wiki/Carnot_cycle http://en.wikipedia.org/wiki/Carnot_cycle [2]: http://en.wikipedia.org/wiki/Rankine_cycle http://en.wikipedia.org/wiki/Rankine_cycle [3]: http://www.brighthubengineering.com/power-plants/32896-how-are-supercritical-boilers-different-from-subcritical-boilers/ http://www.brighthubengineering.com/power-plants/32896-how-a...

neltnerb 12y ago
This is the correct answer. Higher temperature steam allows a higher maximum power extraction potential.

jaggederest 12y ago

For a given megawatt of thermal energy input, you get more electrical output by working in the supercritical steam domain than you do in subcritical systems. So not 'more electricity' since the sun is functionally unlimited, but 'more electricity per square foot' or 'more electricity per heliostat' or what have you.

anthonyb 12y ago

Existing fossil fuel plants (ie. Coal) are designed for supercritical steam. If you can make that with solar, it should make retrofitting much easier.